Various types of communicating device for sending and receiving signals among plural vehicles in order to exchange information have been known so far, and, for example, an inter-vehicle communication system disclosed in JP2001-283381A is capable of communicating information among plural vehicles traveling on a road. The inter-vehicle communication system includes a drive aiding camera mounted on the user's vehicle itself in order to support driving and captures images around the user's vehicle. On the basis of the captured images, traveling related information including a traffic condition around the user's vehicle is detected, and the information is transmitted to the other vehicles by means of a wireless transmitter.
Further, as a technology for general mobile communications, a Multi-hop Wireless Network has been known so far. For example, by means of the Multi-hop Wireless Network, signals can be relayed among moving bodies so that the moving bodies, which cannot directly communicate each other, can indirectly communicate each other. Further, a routing protocol used for building routes of various kinds of Multi-hop Wireless Networks has been developed.
On the road surface, marking lines are painted depending on various purposes in order to recognizing a border line of the traveling lane. The marking line is a solid line, a dashed line or a block type, and its color is white or yellow. These marking lines may be mixed. The lane borderline and a travel guiding line generally indicate a functional marking line, and the white and the yellow line generally indicate a lane mark. The vehicle traveling lane of this invention includes the functional marking line and the lane mark.
Various types of devices for detecting the vehicle traveling lane on the road surface, which is identified with a pair of white lines, have been provided so far. For example, according to a vehicle lane decision apparatus disclosed in JP2003-168198A, the marking lines drawn on the surface of a road is detected from an image captured by a camera, and the marking lines to be a pair of white lines dividing a traveling lane is extracted from them. Then, the interval between the pair of marking lines extracted as the white lines is detected. Under a situation where the interval between the pair of marking lines extracted as the white lines is detected, when the plurality of marking lines adjacent to each other are detected on at least one side of the road from the picture taken from the camera, based on the interval between the pair of marking lines as the white lines detected at the point of time, a pair of marking lines having an interval closest to the interval are extracted as the white lines.
Further, a traveling lane detecting device disclosed in JP2004-118757A includes a low-cost camera for determining a traveling lane in order to assist parking. Such device has been mounted to some kinds of vehicles on the market. Furthermore, a traveling lane detecting means disclosed in JP3520337B2 detects a vehicle traveling lane without using a captured image.
According to the device disclosed in JP2001-283381A, when the user's vehicle detects a traffic condition or abnormal occurrences, it sends the information to all vehicles, which exist within a range where a wireless communication is available. However, because the wireless communication generally uses signals of a high frequency wave, when obstacles such as a building exist between the vehicles, it becomes difficult to communicate between vehicles behind the obstacles.
Further, even when the signals are blocked by a building or the like and cannot be sent and received between two vehicles, using the routing protocol used for building routes of various kinds of Multi-hop Wireless Networks, the signals are relayed by another vehicle and appropriately sent and received between the two vehicles. However, within the Multi-hop Wireless Network between moving bodies such as vehicles, because the signals are randomly hopped, it takes some time to converge the route and communication efficiency is decreased
The traveling lane detecting means disclosed in JP2001-283381A uses a camera, however, such camera is generally expensive and that may enhance the cost of the vehicle communication device as a whole.
A need thus exists to provide a low-cost vehicle communication device that can, even when an obstacle exists between vehicles, a signal is relayed by a vehicle, which is positioned at obstacle-free area and selected to relay the signal, in order to sent and receive the signal appropriately between vehicles.